Academic Degrees

• Ph.D., Biology, University of Rochester (1985) 
• M.S., Biology, University of Rochester (1982) 
• B.S., Biology, Allegheny College (1979)

Professional Experience

• 1985 - 1986, Research Associate, Department of Microbiol., Biochem. and Molec. Biol., Univ. Pittsburgh 
• 1986 - 1989, Post-Graduate Researcher, Department of Plant Pathology, Univ. California-Davis 
• 1989 - 1991, Post-Doctoral Researcher, Department of Biological Sciences, Purdue University

Courses Taught

• Biol 4255/5255  Bacterial Genetics 
• Biol 4000/5000  Environmental Biotechnology I, II, III

Summary of Research

There are currently two main research projects in the laboratory.

One project is to characterize what happens to bacteria when released into the environment. This research focuses on determining the movement, longevity, and physiological status of bacteria in the environment; this field is called bacterial, or microbe, source tracking (BST/MST). We are in the process of developing a BST method that can be used to identify the source of fecal contaminants in surface waters. This project, being done in collaboration with Dr. Helene Hilger (Dept Civil Engineering, UNCC), the North Carolina Dept of Environmental and Natural Resources, and the Mecklenburg County EPA, involves creating and introducing a gfp-tagged natural E. coli isolate into the environment at potential contaminating sites, then monitoring the movement and physiological status of the cells. This new method will be tested in a pilot study approved by the U.S. EPA. In this pilot study the GMO will be introduced into sewer lines known to have leaks, the ability to detect the GMO in water and soil samples will then be determined. Because the GMO detection methods (PCR and FACS) are growth independent, in addition to verifying the source of bacterial pollution, the persistence and physiological status (i.e. whether cells enter the VBNC condition) of bacteria in the environment will also be examined. A patent on this BST method is currently under review and a biotechnology company, BioTrackers, Inc., was formed to explore the commercial applications of this method. The U.S. EPA has supported this research through SBIR funding.

The second research area has as its goal to characterize the role the VBNC condition has in recurrent urinary tract infections (UTIs). The dormant-like viable but nonculturable (VBNC) condition in bacteria is characterized by cells that do not give rise to colonies when plated on non-selective growth medium, yet the cells are viable (as determined microscopically using fluorescent dyes to confirm the presence of intact cell membranes). The VBNC condition can be thought of as a long-term survival strategy when the bacteria are exposed to severe environmental stresses. Cells enter this condition in response to a variety of combinations of environmental stresses such as starvation, temperature shock, and exposure to what are considered to be biocidal agents, such as antibiotics. Because VBNC cells are not detected using conventional microbiology techniques, this condition impacts on strategies to detect microbes, including those designed to detect the presence of pathogens, or to monitor released genetically modified organisms. The VBNC condition has been shown to occur in a wide variety of bacteria, however little is known about what cellular processes occur in this state, what genes are involved in controlling this condition, and what conditions allow cells to resuscitate.

Most UTIs are caused by uropathogenic E. coli (UPEC). The frequency of recurrent UTIs that are caused by the index strain is much higher than would be expected by chance, even though antibiotic therapy should have removed all UPEC cells from the urinary tract. Our hypothesis is that some recurrent UTIs are caused by resuscitation of the UPEC cells that became VBNC during antibiotic therapy. This hypothesis is being tested in vitro, using a mouse model system, and in human UTI patients.

Select Publications

Smith, J., Edwards, J., Hilger, H., and Steck, T.R. Sediment can be a reservoir for coliform bacteria released into streams. J. Gen. Appl. Microbiol. (in press).

Steck, T. R.  2006. The viable but nonculturable condition in bacteria. Encyclopedia of Life Sciences. John Wiley & Sons, Ltd..

Anderson, M., Bollinger, D., Hagler, A., Hartwell, H., Rivers, B., Ward, K., and Steck, T. R. 2004. Viable but nonculturable bacteria are present in mouse and human urine specimens. J. Clin. Microbiol. 42(2):753-758

Grey, B., and Steck, T.R. 2001. Concentrations of copper thought to be toxic to Escherichia coli can induce the viable but nonculturable condition. Appl. Environ. Microbiol. 67(11):5325-5327.

Grey, B., and Steck, T.R. 2001. The viable but non-culturable state of Ralstonia solanacearum may be involved in long-term survival and plant infection. Appl. Environ. Microbiol. 67(9):3866-3872. 

Rivers, B., and Steck, T.R. 2001. Viable but nonculturable uropathogenic bacteria are present in the mouse urinary tract following urinary tract infection and antibiotic therapy. Urol. Res. 29:60-66. 

Ghezzi, J., and Steck, T.R. 1999. Induction of the viable but nonculturable condition in Xanthomonas campestris pv. campestris in liquid microcosms and sterile soil. FEMS Microbiol. Ecol. 30(3):203-208. 

Alexander, E., Pham, D. and Steck, T.R. 1999. The viable but nonculturable condition is induced by copper in Agrobacterium tumefaciens and Rhizobium leguminosarum. Appl. Environ. Microbiol. 65(8):3754-3756. 

Current Lab Members

Deepika Gaddam. M.S. student. Research project - creation of genetically modified E. coli for use in a new bacterial source tracking method.

Kweku Yankson. M.S. student. Research project - optimizing recovery of DNA from soil for use in RT-PCR detection and quantification of GMO.

Keerthi Rallapti. M.S. student. Creation and use of gfp-tagged uropathogenic E. coli (UPEC) cells for use in monitoring the change in physiological status of UPEC during a urinary tract infection.